Fuel injector

ABSTRACT

A fuel injector, in particular for fuel injection systems of internal combustion engines, has a valve closing body which can be operated by an actuator by a valve needle and which cooperates with a valve seat face to form a sealing seat. Swiveling toggle elements are situated between the actuator and the valve needle, so that the actuator acts on first lever arms of the swiveling toggle elements, and second lever arms are mechanically linked to the valve needle.

FIELD OF THE INVENTION

The present invention relates to a fuel injector.

BACKGROUND INFORMATION

German Published Patent Application No. 195 34 445 discusses a fuelinjector having a piezoelectric actuator for operation of a valve needleconnected to a valve closing body. The valve closing body cooperateswith a sealing seat.

It is believed that a disadvantage of this injector is the relativelyshort stroke travel of the piezoelectric actuator, which is composed ofseveral piezoelectric layers arranged in a stack, for the relativelylarge lifting forces.

Furthermore, it is believed that such a fuel injector may be implementedonly as either an inward opening valve or an outward opening valve.Various requirements of such valves, however, may also necessitateoutward or inward opening with a design that is otherwise the same. Tothis end, the working direction of the actuator must be reversed. InGerman Published Patent Application No. 195 00 706, this is apparentlyaccomplished by a hydraulic reversal of direction. The hydraulic devicefor reversal of direction, which may be difficult to implement in thedesign, and the greater space that may be required by such a hydraulicdevice are believed to be disadvantages. Other disadvantages may includehydraulic fluid leakage losses and subsequent negative effects on thefunctioning and lifetime of the hydraulic device and thus the entirefuel injector.

SUMMARY OF THE INVENTION

The fuel injector according to an exemplary embodiment of the presentinvention, is believed to have the advantage that the working directionis reversed by purely mechanical toggle elements. Therefore, it isbelieved that the exemplary embodiment of the present invention may beless susceptible to malfunction, may be advantageous to manufacture andmay require relatively little space.

The reversal of direction achieved by the toggle elements can be used ina variety of ways and is not limited to piezoelectric actuators.

Furthermore, it is believed that by slightly redesigning the toggleelements, the relatively short stroke produced by the piezoelectricactuator can be geared up by lengthening the lever arm, and the strokeacting on the valve needle can be increased.

It is believed that the fuel injector according to the exemplaryembodiment of the present invention is also characterized by a highprecision in the opening and closing times and thus also in the meteredquantity of fuel, because there is no delay in the reversal of directionor in gearing up the stroke.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an axial schematic section through an exemplary embodimentof a fuel injector according to the present invention.

FIG. 2 shows an axial schematic section through another exemplaryembodiment of a fuel injector according to the present invention.

DETAILED DESCRIPTION

FIG. 1 shows an axial sectional diagram through a first exemplaryembodiment of a fuel injector 1 according to the present invention. Thisfuel injector is believed to be especially suitable for direct injectionof fuel, in particular gasoline, into the combustion chamber of aninternal combustion engine, which may be an internal combustion enginehaving fuel mixture compression and spark ignition. The fuel injectorwhich is shown in FIG. 1 is an inward opening fuel injector 1.

Fuel injector 1 has a valve closing body 2 which cooperates with a valveseat face 4 on a valve seat body 3 to form a sealing seat.

An actuator 5 is composed of disk-shaped elements 6, for example, andsurrounds a tubular valve needle 13 in a ring. Disk-shaped elements 6 ofactuator 5 are made of a piezoelectric or magnetostrictive material andcan be glued together. At the end, actuator 5 is secured on a firstlever arm 7 by swiveling toggle elements 8.

Swiveling toggle elements 8 are arranged in a ring around valve needle13, with the ring being divided into several segments.

On their side facing away from actuator 5, swiveling toggle elements 8each have a curved contact face 9 which rests on a first abutment 10 andhas a symmetrical design in FIG. 1.

With a second lever arm 11, swiveling toggle elements 8 act on a drivingpin 12 mounted on valve needle 13. On the end opposite the toggleelements, actuator 5 is attached to a second abutment 14,such as, forexample, by gluing.

As soon as an electric voltage is applied to actuator 5, disk-shapedelements 6 expand and thus exert a force on first lever arms 7 ofswiveling toggle elements 8 due to the resulting stroke. Due to thecurved shape of contact faces 9, second lever arms 11 of swivelingtoggle elements 8 move in the opposite direction and thus also movevalve needle 13 in the same direction by means of driving pin 12, sothat valve closing body 2 which is connected to valve needle 13 islifted up from valve seat face 4. In this way, inward opening fuelinjector 1 is opened and fuel is sprayed through at least one sprayopening 15. The direction of movement of valve needle 13 is illustratedby arrow 22.

FIG. 2 shows an axial section through a second exemplary embodiment of afuel injector 1 according to the present invention. Elements that havealready been described are labeled with the same reference notation tofacilitate a correlation. The description will not be repeated to thisextent.

While fuel injector 1 shown in FIG. 1 has swiveling toggle elements 8with a symmetrically curved contact face 9, contact face 20 in theexemplary embodiment in FIG. 2 is asymmetrical.

In the case of an actuator 5 having the same design in comparison withFIG. 1, the same number of disk-shaped elements 6 and the same electricvoltage, this results in a larger stroke of valve needle 13 via drivingpin 12; thus, the stroke is geared up here.

The present invention is not limited to the exemplary embodiments givenhere and in particular it can also be applied to other actuators, suchas, for example, electromagnetic actuators, as well as other valvedesigns.

What is claimed is:
 1. A fuel injector for a fuel injection system of aninternal combustion engine, the fuel injector comprising: an actuator; avalve needle; and a valve closing body operable by the actuator via thevalve needle, the valve closing body cooperating with a valve seat faceto form a sealing seat; wherein: at least one swiveling toggle element,having a first lever arm and a second lever arm, is situated between theactuator and the valve needle; the actuator acts on the first lever armof the at least one swiveling toggle element; and the second lever armof the at least one swiveling toggle element is at least one ofmechanically linked and operatively connected to the valve needle; andan actuation direction of the actuator and a movement direction of thevalve needle are arranged in parallel opposite directions.
 2. The fuelinjector of claim 1, wherein each of the at least one swiveling toggleelement is supported on a first abutment.
 3. The fuel injector of claim2, wherein each of the at least one swiveling toggle element includes acurved contact face on which it rests on the first abutment.
 4. The fuelinjector of claim 1, wherein a curved contact face of each of the atleast one swiveling toggle element has a symmetrical curvature.
 5. Thefuel injector of claim 1, wherein a curved contact face of each of theat least one swiveling toggle element has an asymmetrical curvature. 6.The fuel injector of claim 1, wherein each of the at least one swivelingtoggle element acts on a driving pin provided on the valve needle, thevalve needle being axially arranged.
 7. The fuel injector of claim 1,wherein each of the at least one swiveling toggle element includesasymmetrical lever arms, and a stroke induced by the actuator is gearedup.
 8. The fuel injector of claim 1, wherein the actuator includes atleast one of a piezoelectric actuator and a magnetostrictive actuatorwhich is correspondingly composed of one of piezoelectric disk-shapedelements and magnetostrictive disk-shaped elements arranged in a stack.9. The fuel injector of claim 1, wherein the at least one swivelingtoggle element includes a plurality of swiveling toggle elementsarranged in a ring.
 10. The fuel injector of claim 1, wherein theactuator is arranged between the at least one swiveling toggle elementand an abutment to reverse a direction of a force exerted on the atleast one swiveling toggle element.
 11. A fuel injector for a fuelinjection system of an internal combustion engine, the fuel injectorcomprising: an actuator; a valve needle; and a valve closing bodyoperable by the actuator via the valve needle, the valve closing bodycooperating with a valve seat face to form a sealing seat; wherein atleast one swiveling toggle element, having a first lever arm and asecond lever arm, is situated between the actuator and the valve needle;wherein the actuator acts on the first lever arm of the at least oneswiveling toggle element; wherein the second lever arm of the at leastone swiveling toggle element is at least one of mechanically linked andoperatively connected to the valve needle; wherein each of the at leastone swiveling toggle element is supported on a first abutment; andwherein each of the at least one swiveling toggle element includes acurved contact face on which it rests on the first abutment.
 12. Thefuel injector of claim 11, wherein a curved contact face of each of theat least one swiveling toggle element has one of a symmetrical curvatureand an asymmetrical curvature.
 13. The fuel injector of claim 11,wherein each of the at least one swiveling toggle element acts on adriving pin provided on the valve needle, the valve needle being axiallyarranged.
 14. The fuel injector of claim 11, wherein each of the atleast one swiveling toggle element includes asymmetrical lever arms, anda stroke induced by the actuator is geared up.
 15. The fuel injector ofclaim 11, wherein the actuator includes at least one of a piezoelectricactuator and a magnetostrictive actuator which is correspondinglycomposed of one of piezoelectric disk-shaped elements andmagnetostrictive disk-shaped elements arranged in a stack.
 16. A fuelinjector for a fuel injection system of an internal combustion engine,the fuel injector comprising: an actuator; a valve needle; and a valveclosing body operable by the actuator via the valve needle, the valveclosing body cooperating with a valve seat face to form a sealing seat;wherein at least one swiveling toggle element, having a first lever armand a second lever arm, is situated between the actuator and the valveneedle; wherein the actuator acts on the first lever arm of the at leastone swiveling toggle element; wherein the second lever arm of the atleast one swiveling toggle element is at least one of mechanicallylinked and operatively connected to the valve needle; and wherein the atleast one swiveling toggle element includes a plurality of swivelingtoggle elements for forming one of ring segments and a ring part. 17.The fuel injector of claim 16, wherein a curved contact face of each ofthe at least one swiveling toggle element has one of a symmetricalcurvature and an asymmetrical curvature.
 18. The fuel injector of claim16, wherein each of the at least one swiveling toggle element acts on adriving pin provided on the valve needle, the valve needle being axiallyarranged.
 19. The fuel injector of claim 16, wherein each of the atleast one swiveling toggle element includes asymmetrical lever arms, anda stroke induced by the actuator is geared up.
 20. The fuel injector ofclaim 16, wherein the actuator includes at least one of a piezoelectricactuator and a magnetostrictive actuator which is correspondinglycomposed of one of piezoelectric disk-shaped elements andmagnetostrictive disk-shaped elements arranged in a stack.
 21. A fuelinjector for a fuel injection system of an internal combustion engine,the fuel injector comprising: an actuator; a valve needle; and a valveclosing body operable by the actuator via the valve needle, the valveclosing body cooperating with a valve seat face to form a sealing seat;wherein at least one swiveling toggle element, having a first lever armand a second lever arm, is situated between the actuator and the valveneedle; wherein the actuator acts on the first lever arm of the at leastone swiveling toggle element; wherein the second lever arm of the atleast one swiveling toggle element is at least one of mechanicallylinked and operatively connected to the valve needle; wherein each ofthe at least one swiveling toggle element is supported on a firstabutment; and wherein a direction of a force exerted on the at least oneswiveling toggle element is reversed due to an arrangement of theactuator between the at least one swiveling toggle element and a secondabutment.
 22. The fuel injector of claim 21, wherein a curved contactface of each of the at least one swiveling toggle element has one of asymmetrical curvature and an asymmetrical curvature.
 23. The fuelinjector of claim 21, wherein each of the at least one swiveling toggleelement acts on a driving pin provided on the valve needle, the valveneedle being axially arranged.
 24. The fuel injector of claim 21,wherein each of the at least one swiveling toggle element includesasymmetrical lever arms, and a stroke induced by the actuator is gearedup.
 25. The fuel injector of claim 21, wherein the actuator includes atleast one of a piezoelectric actuator and a magnetostrictive actuatorwhich is correspondingly composed of one of piezoelectric disk-shapedelements and magnetostrictive disk-shaped elements arranged in a stack.